Magnesium spray for feet is a topical cosmetic product containing magnesium chloride in water, applied directly to the skin rather than taken orally. Advocates suggest it may help with muscle cramps, relaxation, and sleep quality through transdermal absorption. However, scientific evidence supporting significant magnesium absorption through the skin remains limited and inconclusive. The thick skin on the soles of the feet may actually reduce absorption. Whilst these products are widely available in the UK, they are not licensed medicines, and claims should be approached with caution. If you experience persistent muscle cramps or suspect magnesium deficiency, consult your GP for proper assessment and evidence-based treatment.

What Is Magnesium Spray and How Does It Work?

Magnesium spray is a topical formulation containing magnesium chloride dissolved in water, designed for transdermal application to the skin. Unlike oral magnesium supplements, which must pass through the digestive system, magnesium spray is applied directly to the skin surface. These products are typically classified as cosmetics rather than licensed medicines in the UK.

The proposed mechanism of action centres on transdermal absorption, whereby magnesium ions potentially penetrate the stratum corneum (the outermost layer of skin) and enter local tissues. Magnesium is an essential mineral cofactor involved in over 300 enzymatic reactions in the body, including muscle contraction and relaxation, nerve function, energy production, and protein synthesis. Advocates suggest that topical application may help address localised muscle tension.

However, it is important to note that scientific evidence supporting significant transdermal magnesium absorption remains limited and inconclusive. Whilst some small studies have suggested modest increases in magnesium levels following topical application, the clinical significance of these findings is uncertain. The skin's barrier function is specifically designed to prevent the passage of ions and water-soluble substances, which may limit the extent to which magnesium can penetrate effectively. The skin on the soles of the feet is actually thicker than elsewhere on the body, potentially reducing rather than enhancing absorption. There is no official link established by regulatory bodies such as the MHRA or NICE between topical magnesium application and clinically meaningful changes in magnesium status.

Despite the lack of robust evidence, magnesium spray products are widely available as cosmetic preparations and are marketed for muscle relaxation, cramp relief, and general wellbeing. Consumers should approach such claims with appropriate caution and maintain realistic expectations regarding efficacy. If you suspect you have a magnesium deficiency, it is advisable to consult your GP for proper assessment and evidence-based management, which may include dietary changes or oral supplementation.

Benefits of Using Magnesium Spray on Feet

Proponents of magnesium spray for feet cite several potential benefits, though it is essential to recognise that many of these claims are based on anecdotal reports rather than high-quality clinical evidence. The most commonly reported benefit is relief from muscle cramps and tension, particularly nocturnal leg cramps that affect the feet and calves. Magnesium plays a crucial role in muscle relaxation by regulating calcium influx into muscle cells, and deficiency has been associated with increased muscle excitability. However, systematic reviews have found inconsistent evidence that magnesium supplementation—oral or topical—reliably prevents or treats muscle cramps in the general population.

Some users report that applying magnesium spray to the feet before bedtime may promote relaxation and improved sleep quality. Magnesium is involved in the regulation of neurotransmitters and the hypothalamic-pituitary-adrenal axis, which governs stress responses. Whilst oral magnesium supplementation has shown some promise in supporting sleep in individuals with deficiency, there is no established evidence that topical application to the feet produces similar effects.

Additionally, magnesium spray is sometimes used by athletes or physically active individuals who believe it may aid post-exercise recovery and reduce delayed-onset muscle soreness (DOMS). However, robust clinical trials demonstrating efficacy are lacking.

Other purported benefits include softening of hard skin on the feet and a general sense of wellbeing and stress reduction.

It is important to emphasise that these benefits are largely subjective and not supported by NICE guidance or peer-reviewed evidence. For nocturnal leg cramps, evidence-based self-care measures include regular calf stretching exercises, staying hydrated, and reviewing medications with your GP that might contribute to cramps.

Individuals experiencing persistent muscle cramps, sleep disturbances, or other symptoms should consult their GP to exclude underlying medical conditions such as magnesium deficiency, peripheral neuropathy, or restless legs syndrome, which may require specific investigation and treatment according to NICE Clinical Knowledge Summaries guidance.

How to Apply Magnesium Spray to Your Feet Safely

If you choose to use magnesium spray on your feet, proper application technique can help maximise comfort and minimise potential adverse effects. Before first use, it is advisable to perform a patch test on a small area of skin to check for sensitivity or irritation, particularly if you have a history of sensitive skin or dermatological conditions.

Application steps:

1. Cleanse the feet thoroughly – Wash your feet with mild soap and water, then pat dry. Clean skin may facilitate better contact with the spray formulation.

2. Shake the bottle well – This ensures the magnesium chloride is evenly distributed throughout the solution.

3. Spray directly onto the skin – Hold the bottle as directed by the manufacturer and apply according to the product instructions. Avoid broken skin, open wounds, or areas of active infection.

4. Massage gently – Use your hands to rub the solution into the skin, which may provide a soothing effect. Some users prefer to leave the spray on without rubbing.

5. Allow time to absorb – Follow the manufacturer's guidance regarding absorption time. Be aware that magnesium chloride can feel slightly sticky or cause a tingling sensation initially.

6. Rinse if desired – If the residue feels uncomfortable, you may rinse your feet with water after the absorption period.

Frequency of use should follow the manufacturer's recommendations. Start with a lower frequency to assess tolerance.

Important safety considerations:

• Avoid contact with eyes and mucous membranes

• Do not apply to freshly shaved skin or areas with cuts or abrasions

• Wash hands thoroughly after application

• Store the product away from children

• If using other topical preparations on your feet (e.g., antifungal creams, emollients), space applications by at least 30-60 minutes to avoid dilution

• People with diabetes or peripheral neuropathy should take extra care to avoid application to broken skin and should seek podiatry advice for foot problems

If you experience persistent discomfort, irritation, or any unexpected symptoms following use, discontinue application and seek advice from your GP or pharmacist.

Potential Side Effects and Who Should Avoid It

Whilst magnesium spray is generally considered safe for topical use, some individuals may experience adverse effects, most commonly related to local skin irritation. The most frequently reported side effect is a tingling, stinging, or burning sensation at the application site, which typically occurs shortly after spraying and may last for several minutes. This sensation is thought to result from the high concentration of magnesium chloride and its interaction with the skin's surface. The intensity often diminishes with regular use as the skin acclimates, though some individuals find it persistently uncomfortable.

Other potential side effects include:

• Skin dryness, flaking, or itching

• Redness or mild rash at the application site

• Sticky residue on the skin

• Rarely, allergic contact dermatitis in sensitive individuals

If severe irritation, blistering, or signs of an allergic reaction (such as widespread rash, swelling, or difficulty breathing) occur, discontinue use immediately and seek medical attention. For severe allergic reactions, call 999 or go to A&E.

Who should avoid magnesium spray or use it with caution:

• Individuals with broken or damaged skin – Application to cuts, wounds, eczematous areas, or other compromised skin can cause significant stinging and may delay healing.

• Those with known sensitivity to magnesium chloride – Although rare, some people may have hypersensitivity to the formulation.

• People with severe renal impairment – Although systemic absorption through the skin is likely minimal, individuals with kidney disease should exercise caution with any form of magnesium supplementation, as impaired renal function reduces the body's ability to excrete excess magnesium. Consult your GP or nephrologist before use.

• Pregnant or breastfeeding women – There is insufficient evidence regarding the safety of topical magnesium products during pregnancy and lactation. Seek advice from your midwife or GP before use.

• People with diabetes – Take extra care with foot applications, especially if you have neuropathy or circulatory problems. Never apply to broken skin or foot ulcers, and maintain regular podiatry care.

• Children – The safety and appropriate dosing of magnesium spray in paediatric populations have not been established. Parental supervision and professional guidance are recommended.

When to seek medical advice: If you are considering magnesium spray to address specific symptoms such as persistent muscle cramps, restless legs, or sleep disturbances, it is advisable to consult your GP first. These symptoms may indicate underlying conditions requiring investigation, such as electrolyte imbalances, peripheral vascular disease, or neurological disorders. NICE Clinical Knowledge Summaries recommend that muscle cramps persisting despite simple measures warrant clinical assessment to exclude secondary causes. Seek urgent medical attention for unilateral calf swelling or redness, which could indicate a blood clot.

Your GP may arrange blood tests to check magnesium levels and other relevant parameters, and can advise on evidence-based treatments tailored to your individual circumstances.

Suspected adverse reactions to magnesium spray can be reported through the MHRA Yellow Card Scheme.

Frequently Asked Questions